Expansion joints are commonly found in various forms of artificial ground cover, including concrete forms such as sidewalks, driveways and other slab structures. Expansion joints may also be used in other forms of ground cover that may be comprised of masonry, various metals, and other such materials that are prone to expansion and contraction throughout seasonal temperature changes. The expansion joints help to cushion the effect of expansion and contraction, thus preventing cracking, heaving and other such ill effects.
Expansion joints are typically formed from durable, resiliently deformable materials. Fiber-board is an example of one common expansion joint material which is formed from natural and man-made fibers that are bonded together using asphalt or other known bonding agents. Other expansion joint materials include closed-cell polyfoam, rubber, cork, cross-linked ethylene vinyl acetate and closed-cell neoprene. The expansion joint material selected may depend upon various factors presented in each particular application. Some factors may include cost, climate and type of material used in the formation of the artificial ground cover. Regardless of their construction, expansion joint materials are typically formed to have a thickness that ranges between ¼ of an inch to 1 inch. Common widths range from 3 inches to 12 inches and their lengths are commonly found in four to ten foot sheets.
Commonly, expansion joint material is positioned adjacent an existing section of ground cover, such as concrete, prior to applying new ground cover immediately adjacent thereto. In instances where expansion joint material is to be positioned in an area where no existing ground cover exists, contractors typically position ½″×4″ or 1″×4″ backboard behind the expansion joint material and stake the backboard in place. The new ground cover is then applied over the ground surface adjacent the expansion joint material. Once the ground cover has sufficiently cured, the backboard and stakes are removed and the next section of ground cover may be applied to the ground surface, adjacent the opposite side of the expansion material. This method of forming an expansion joint has several shortcomings. First, the ground cover is applied to the ground surface in multiple stages over a period of two or more days. The increased number of trips to and from a job-site become time consuming and expensive over time. Secondly, as depicted in FIG. 2, expansion joint material is frequently provided in widths that are insufficient to span the full thickness of the ground cover being applied. Accordingly, as the ground cover is applied to the ground surface adjacent the expansion joint material, the ground cover will not be segregated from adjacent, existing ground cover. This results in the two sections of ground cover being abutted immediately adjacent one another and defeats the purpose of installing an expansion joint at this location. In other instances, also depicted in FIG. 2, the ground surface is improperly prepared, leaving depressions or other recesses at the location where an expansion joint is required. In these instances, expansion joint material that would otherwise be of sufficient width for the thickness of ground cover being applied will be insufficient to span the distance from the bottom of the depression to the surface of the ground cover being applied. The result will produce a single section of ground cover without the appropriate expansion joint structure.
Accordingly, what is needed is a novel system and method for forming expansion joints that enables a user to prepare an entire site for a single pour or application of artificial ground cover. Such a novel system and method should also enable a user to vary the vertical positioning of expansion joint material in a given location while effectively segregating adjacent sections of ground cover.